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How dirty is the Willamette, really?

Can the river that runs through farms in the Willamette Valley, Oregon's largest metropolitan area and a Superfund site really be clean enough to swim in? Yes, as long as it hasn't rained in the past 48 hours.

Yes, that Willamette. The one that runs through downtown Portland carrying agricultural runoff, municipal wastewater, the occasional flush of raw sewage, and the remnants of now-banned industrial toxins.

For all its problems, the environmental nonprofit Riverkeeper says, the river’s really not that dirty anymore. Especially in downtown Portland in the summer when it’s not raining.

I wanted to investigate this claim a bit before I consider jumping in on Sunday. I talked with water quality officials at the Environmental Protection Agency, Oregon Department of Environmental Quality and Portland Bureau of Environmental Services.

Here’s what I learned:

All three agencies agree the river is safe for swimming as long as there has not been a combined sewer overflow within the past 48 hours.

That conclusion is based on two basic facts: One, E. coli bacteria are well below health hazard levels. Two, all other potentially health threatening toxins are way below the levels at which a swimmer would be affected.

“Toxics and that type of pollution are very real and will continue to be a real problem when see it in fish tissue, macro invertebrates and birds,” said Travis Williams, executive director for Willamette Riverkeeper. It’s not a good thing for ecosystem and health of fish and wildlife. … But it wouldn’t hurt you as a human unless you were floating in the river for 1,000 years.”

Two days after the city releases combined sewer and stormwater into the river, it’s gone from downtown Portland.

Check out the difference in the average E. coli levels before and after the West Side Big Pipe project was completed. Imagine how E. coli free the river will be when the East Side Pipe is finished this fall. This chart from Portland's Bureau of Environmental Services, represents the average of monthly water samples from the east, west and middle sections of the river starting in 1995.

Since the city has put in the big pipe on the west side of the river, E. coli bacteria levels are noticeably lower (see chart above).

“It’s really dropped off dramatically, especially in the summer,” said Duane Linnertz, investigations and monitoring manager for Portland Bureau of Environmental Services. “If you go out there in the winter, it’s a whole different story. We only dirty it up when it rains. Most of the time, when it’s not raining, it’s a pretty clean river.”

Once the big pipe project is finished on the east side of the river, sending combined sewer and stormwater to a wastewater treatment plant instead of spilling it directly into the river, raw sewage will only enter the river four times per winter and once every three summers, according to the Portland Bureau of Environmental Services.

A person would have to spend a very long time in the river (like hundreds of years) or be exposed to much higher concentrations of heavy metals, industrial compounds, flame retardants, agricultural chemicals and pharmaceuticals to reach the level of exposure health officials worry about. But fish and wildlife are another story, and we do have to worry about the effects of eating critters that live in contaminated waters.

“The levels of these toxic contaminents relative to human exposure risk are very low,” said Doug Drake, lower Willamette Basin coordinator for Oregon Department of Environmental Quality. “In the sediments themselves, the concentrations can be a little higher, but even that exposure – walking through mud that might be a little higher – isn’t something that can do much in terms of affecting human health. It’s more the critters that live in the mud and fish that eat the critters. It takes time for toxins to accumulate in the tissue of those organisms and then pose a risk to fish. It’s not an acute toxicity problem. It’s usually a body burden issue if fish farther up the food chain are consumed by humans. The concentrations in fish are right at the threshold where we’d want pregnant women and children to be conscious of how much fish they’re eating.”

Dilution is still a solution to pollution. And so are deep tunnels.

“The river is definitely cleaner than it was. That part is clear,” said Joel Salter, water programs coordinator for the Environmental Protection Agency. “What’s cleaned it up is the deep tunnels.”